1. Field of the Invention
The present invention relates to novel pyrimidine compounds or their salts, herbicidal compositions containing them, and a herbicidal method for applying them.
2. Discussion of Background
Recently, a number of herbicides have been developed and practically used, and they have contributed to the saving of energy for the agricultural operations and to the improvement of the production efficiency. Further, it has been known that various 2-phenoxypyrimidine derivatives are effective as herbicides ((1) U.S. Pat. No. 4,770,691, (2) U.S. Pat. No. 4,427,437 and (3) Agr. Biol. Chem. Vol. 30, No. 9, p. 896 (1966)).
However, the compounds disclosed in the above reference (1) have a problem with respect to the safety to crop plants, although they have exhibited high herbicidal effects. On the other hand, the compounds disclosed in the above references (2) and (3) have drawbacks that their herbicidal activities against annual weeds are inadequate, and they exhibit no substantial activities against perennial weeds.